An analysis of 7 cases of thoracic actinomycoses were recorded over 25 years enabling a better appreciation of the radiological and clinical criteria: a low grade pneumonia with haemoptysis and an alteration in the general physical state, with pseudo-tuberculous radiological images or "pseudo-tumoral" with bronchograms and parietal wall disease. This clinical picture calls for endoscopic biopsies or biopsies under CT scanning for a study combining both histological and bacteriological diagnosis on appropriate culture media, enabling an exploratory thoracotomy to be avoided, the latter the classic method of diagnosis. This approach should reduce the number of pneumonias which are not confirmed bacteriologically which are sensitive to the usual antibiotics and determine better the true frequency of actinomycoses.